We Americans tend to overestimate, I think, the extent to which Islam permeates daily life in the Arab world.

While one can hear the call to prayer ("Allahu ... Akhbar") repeated loudly from most quarters of Cairo at the appropriate times, only true believers appear to actually perform their Islamic duty with regularity. While it was common to see a fewmen praying on carpets outside the smaller, newer mosques in commercial areas (they're kind of like convenience stores for religion), only on Friday did I see any mosques filled anywhere near to capacity.

Nonetheless, a very large percentage of men in Cairo do have a dark, raised spot on their forehead indicating a lifetime devoted to prayer. I think most people must pray privately, or not at all.